JPS621273A - Reverse-conducting gto thyristor - Google Patents

Abstract

PURPOSE:To compound a diode having small forward voltage adjacently into one semiconductor substrate, and to ensure even reverse with-standing voltage between a gate and a cathode by thinning the diode section for a reverse- conducting GTO thyristor while forming the same conduction type high impurity concentration layer to the surface of a thinned layer. CONSTITUTION:A p-layer 22 for a diode section is made thinner than a p-base layer 13 for a GTO thyristor section through etching, etc. A p<+> layer 5 is shaped onto the surface of the p-layer 22, and functions as the stoppage of the extension of a depletion layer. A diode anode electrode 9 being in contact with the p<+> layer 5, thyristor cathode electrodes 7 being in contact with an n-emitter layer 14, gate electrodes 8 being in contact with the p base layer 13 and a thyristor anode electrode 6 serving as a diode cathode electrode being in contact with a p-emitter layer 11 are formed severally, and an electrode body 10 with a stepped section is pressure-welded to the thyristor cathode electrodes 7 and the diode anode electrode 9. A resistor 20 is shaped, thus ensuring withstanding voltage between a gate and a cathode for the thyristor without scaling up an isolation region 3.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a reverse conducting GTO thyristor as a composite element in which a GTO thyristor and a diode antiparallel to the GTO thyristor are provided in the same semiconductor substrate.

[Prior art and its problems]

In a GTO inverter as shown in Fig. 2, a GTO thyristor 31 and a diode 3 are connected in antiparallel.
2 are integrated to simplify the circuit configuration. In such a reverse conduction GTO thyristor, the controllable current is large, the reverse recovery time of the diode part is short, and the withstand voltage between the gate and cathode must be high in order to turn off the large current. It is necessary to have high pressure resistance.

[Purpose of the invention]

The present invention is a reverse-conducting GTO thyristor that satisfies the above conditions, that is, a reverse-conducting GTO thyristor with a large controllable current, a short reverse recovery time of the diode part, a high breakdown voltage between the gate and the cathode, and a high thyristor forward breakdown voltage. The purpose is to provide thyristors.

[Key points of the invention]

The present invention provides an extension of a pn junction between a GTO thyristor part made of four pnpn layers and provided with a gate electrode in contact with a base layer of a first conductivity type, and a base layer of a second conductivity type adjacent to the base layer. A layer of the first conductivity type of the diode part of a transparent 11GTo thyristor having a diode part consisting of 912 layers sandwiching surfaces in the same semiconductor substrate is thinner than the base layer of the first conductivity type of the GTO thyristor part, and is thinner than the base layer of the first conductivity type of the GTO thyristor part. The above object is achieved by connecting the electrode which is in contact with the first conductivity type layer with a higher concentration at the surface to the main electrode which is in contact with the second conductivity type emitter layer of the GTO thyristor section.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which a silicon substrate has a G
TO thyristor section 1, diode section 2 and isolation region 3
is formed. GTO thyristor section l has p emitter 11111. n base layer 12. p-hose layer 13. n
The diode section 2 consists of an emitter layer 14 and an 0 layer 21.
It consists of nine layers 22, the side surface 18 is bevel-shaped, and the pn junction of the diode part and the J8 junction between the p+n base layers of the GTO thyristor part are continuous. On the side of the n base layer 12 and the 0 layer 21 far from this pn junction, an n'' layer 4 is formed by phosphorus diffusion or the like, using a known technique to create a substantially pin structure. The layer 22 is made thinner than the p base layer 13 of the GTo thyristor section by etching etc. By making p122 thinner, the forward voltage V of the diode can be maintained even if the amount of lifetime killer introduced into the diode section is increased. Since the voltage is not increased excessively, the lifetime of the diode section can be shortened, and a high-speed diode with a short reverse recovery time can be achieved. When the voltage is applied, the depletion layer that spreads in the 9th layer 22 of the diode part
In order to prevent the depletion layer from reaching the anode electrode of the diode section, which has the same potential as the cathode electrode of the thyristor section, a p layer 5 is formed on the surface of the nine layer 22 by boron diffusion, etc., and serves to stop the spread of the depletion layer. As a result, it is easy to ensure the forward breakdown voltage of this reverse conducting GTO thyristor. Diode anode electrode 9 in contact with this 99 layer 5. Thyristor cathode electrode 1 in contact with n emitter layer 14. Gate voltage $1+8. in contact with p base layer 13. A thyristor 7-node electrode 6 which also serves as a diode cathode electrode in contact with the p emitter layer 11 is provided, and the thyristor cathode electrode 7 and the diode anode electrode 6 are connected to each other. ! The electrode body 10 having a step is pressed into contact with i9. In the GTO thyristor section 1, when a reverse voltage is applied between the gate electrode WIB and the cathode electrode 7 to turn it off, there is a high resistance between the diode anode electrode 9 and the thyristor cathode electrode 7, which are in contact with the same pWA as the gate electrode 8. However, according to the present invention, there is a step between the two and a resistor 20 is formed, so that the isolation region 3 can be removed without increasing the size of the gate. Withstand voltage between cathodes is ensured. Now, as indicated in Fig. 1, the height from the J-junction of the GTO silisk section that is continuous to the p-n junction of the diode section to the surface of the n emitter layer 14 is H5. If the step to the surface is h, if h is also made larger, the thickness of the second layer side of the diode part 2 will be thinner,
As mentioned above, even if the lifetime is shortened (the forward voltage can be suppressed, the speed of the diode section can be increased), and the resistance 20 of the isolation region 3 is also large (as a result, the resistance between the gate and cathode of the GTO thyristor section 1 is A sufficient reverse voltage can be applied to , and at the same time, current seepage from the diode section 2 during turn-off is reduced, increasing the controllable current of the GTO thyristor. However, if h is made too large, the forward breakdown voltage becomes small. Figure 3 shows a silicon substrate with a thickness t of 45 On, a reverse conduction GTO thyristor with a p emitter layer height H of 100#111 + width W of the isolation part 3 of about 1 inch, and forward breakdown voltage and controllable h. From this result, which shows the relationship with the current, 60μ≦h≦75
β1, that is, the thickness of the diode part is 375 to 390μ
It was found that a controllable current of 2000 A and a breakdown voltage of 2500 V were obtained. [Effects of the Invention] According to the present invention, the thickness of the diode portion of a reverse conduction GTO thyristor is reduced, and a highly impurity concentration layer of the same conductivity type is formed on the surface of the thinned layer to prevent the spread of a depletion layer. By providing a GTO thyristor with a large controllable current and a high-speed diode with a low forward voltage, it is possible to combine them in close proximity in one semiconductor substrate. The effect obtained is extremely large because it can also ensure road pressure resistance.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of essential parts of an embodiment of the present invention, Fig. 2 is a GT
The circuit diagram of the O inverter, FIG. 3, is a diagram showing the relationship between the size h of the step formed by the present invention, the forward breakdown voltage, and the controllable current of the reverse conduction GTO thyristor. 1: GTO thyristor section, 2: diode section, 3: separation region, 7: cathode electrode, 8: gate electrode, 9: diode anode electrode, 10: electrode body, h: step. Figure 1 Figure 2

Claims (1)

[Claims] 1) A GTO thyristor section consisting of four adjacent layers having alternately different conductivity types and provided with a gate electrode in contact with a base layer of a first conductivity type, and a base of a second conductivity type adjacent to the base layer. In a semiconductor substrate having a diode section consisting of two layers of different conductivity types sandwiching an extension surface of a pn junction between the two layers, the first conductivity type layer of the diode section is the first conductivity type layer of the GTO thyristor section following it. The electrode that is in contact with the first conductivity type layer, which is thinner than the base layer of the conductivity type and has a higher concentration on its surface, is connected to the main electrode that is in contact with the emitter layer of the second conductivity type of the GTO thyristor section. Features reverse conduction GTO thyristor.